In order to describe temporal and spatial variations in water quality and to identify pollution sources, water quality of a typical constructed wetland in Olympic Forest Park of Beijing was evaluated. Fuzzy Comprehensive Assessment (FCA) was applied to estimate the overall water situation of each season/functional area. Hierarchical Discriminant Analysis (HDA), together with Spearman Correlation Analysis, was used to identify significant parameters. Principal Component Analysis/Factor Analysis (PCA/FA) was applied to extract the responsible sources/factors in each season. The results demonstrated relatively high water quality of the constructed wetland in Olympic Forest Park, which was suitable for landscape reuse. The most severe contamination occurred in autumn (temporal scale) and main lake/mixed oxidation pond (spatial scale). CODMn, NO3 --N, ORP and TN accounted for 91.8% of total temporal variance and thus monitoring should be strengthened; Chl-a, CODMn, DO and pH account for 55.1% of total spatial variance, and the low accuracy in HDA indicated similar pollution characteristics within these 5 function areas. Internal pollution was the major pollutant source in all selected seasons. The constructed wetland was largely affected by organic matters in spring, was contaminated by nutrient pollutant (N and P) in summer, and was threatened by eutrophication in autumn. The major source in reclaimed water treatment area was nutrient pollutant (N and P), while internal pollutant dominated in other functional areas. Enhancing the water circulation and shortening the hydraulic retention time can effectively degrade the effect of nutrient salts and organic pollutants.

Reclaimed water as supplemental source of urban rivers and lakes is regarded as an important approach to improve urban aquatic ecological environment. However, high concentration of nitrogen and phosphorus from reclaimed water can easily lead to eutrophication. Bacteria in constructed wetland are known to play an important role in aquatic ecological remediation. The community structure and diversity of cultural associated bacteria in roots of reed (phragmites australis) growing in reclaimed water management system (reclaimed water treatment unit, cycling water treatment unit, oxidation ponds) in Beijing Olympic Park was investigated in summer and autumn by 16S rDNA cloning, Amplified Ribosomal DNA Restriction Analysis (ARDRA), and sequence homology comparison. Canonical Correspondence Analysis (CCA) and Two way Indicator Species Analysis (TWINSPAN) were used to estimate and statistical test the effects of environmental variables and other explanatory variables on bio-communities, especially to unravel the simultaneous response of the species in a bacteria community to environmental variations when the effects are hidden by other large sources of variation. Cluster analysis on bacteria clones showed that 29 operational taxonomic units (OTUs) were identified based on the similarity of ARDRA banding profiles in 328 cultural clones. Environmental changes resulted into a seasonal shift of bacteria community on community density and diversity in reclaimed water management system. Community density and evenness of root-associated aerobic bacteria in summer increased 76. 37% -96. 70% than those in autumn. Kinds of inflow (reclaimed water or cycling water) and types of matrix both contributed to spatial variability of bacterial community. There was relative high community diversity and density with reclaimed water inflow and IVCW matrix in reclaimed water treatment unit. Spatial variability of bacteria community in summer increased with altering dominant species in each unit and more accidental species. Therefore, reclaimed water treatment unit in summer with the highest community density (29. 9 × 107 CFU/ g roots weight) and the Shannon-Weaver (H'=1. 824). CCA and TWINSPAN analysis revealed that OTU1 and OTU28 in constructed wetland system were with the wide ecological amplitude, which contributed to the stability of constructed wetland system and hardly disturbed by water viabilities, played an important role in material metabolism and energy metabolism. NH+ 4,TN,ORP,TP in water drived seasonal variability of community structure of reed root-associated aerobic bacteria, while NO- 3, TDS, pH, Sal in water leaded to spatial variability community structure of reed root-associated aerobic bacteria of summer reclaimed management system.

By means of the gravity recovery and climate experiment ( GRACE) satellite and the global land data assimilation system (GLDAS), the change of groundwater storage in the Haihe River Basin over 72 consecutive months from 2004 to 2009 was investigated. On such a basis, a binary regression model for groundwater exploitation, the annual change of groundwater storage, and annual rainfall of the GRACE satellite was established based on the previously published data of rainfall and groundwater exploitation in the Haihe River Basin from 2004 to 2009. The change of groundwater storage derived from the GRACE and GLDAS data has a good correlation with the observed data, and the R2 is 0.804. Based on the annual data of change of groundwater storage and the annual rainfall data of the GRACE satellite, the estimated results of the groundwater exploitation are satisfactory, and the R2 of the binary regression model is 0.787, indicating that using the GRACE satellite data to estimate the groundwater exploitation is feasible and is a good complementary evaluation method for the traditional terrestrial investigation.